Lately, various media such as DVDs (Digital Versatile Disc), Blu-ray Discs (registered trademark) and flash memories are used as information recording media. Particularly, lately, use of memory cards such as USB memories on which large volume flash memories are mounted is becoming popular. A user can record content such as music or a movie in various information recording media, attach the media to a playback apparatus (player) and play back content.
However, creators or distributors hold copyrights and distribution rights of a great number of items of content such as music data and image data. Hence, when content is provided to the user, fixed usage control, that is, control to permit only a user who has a valid usage right to use content and prevent unregulated usage such as copy without permission is generally performed.
For example, an AACS (Advanced Access Content System) is known as a standard related to content usage control. The AACS standard defines a usage control configuration with respect to, for example, recorded content of a Blu-ray Disc (registered trademark). More specifically, the AACS standard defines, for example, an algorithm which can limit users who can acquire an encryption key of content to be recorded in a Blu-ray Disc (registered trademark) as encrypted content to a valid user.
The AACS defines managed copy (MC) which specifies a condition that copy permission information is acquired from a management server when, for example, content is copied between media.
Further, as processing of downloading content from a server, the AACS defines various downloads modes such as
EST (Electric Sell Through) which uses a user apparatus such as a PC and
MoD (Manufacturing on Demand) which uses a shared terminal installed at a convenience store, and
sets an obligation to perform processing according to a predetermined rule even when content is recorded in a disk by each download processing and used.
In addition, these processing is disclosed in, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-98765).
However, the present AACS defines a configuration of controlling usage of content recorded in a disk such as a Blu-ray Disc (registered trademark), and does not sufficiently define content to be recorded in other media such as a flash memory of a memory card.
Further, to playback content according to a content protection system (CPS) which is defined by the AACS, a playback apparatus needs to employ a configuration of executing a playback program (application) defined by the AACS.
However, a problem is that this playback program (application) defined by the AACS is a program which can be used only by a device having a specific specification, and is not a program which can be used by all devices.
For example, Android which provides an operating system (OS) function which is generally used by mobile terminals lately has difficulty in executing processing related to a content protection system (CPS) by means of the above application defined by the AACS.
For example, the content protection system (CPS) defined by the AACS employs a configuration of recording various independent files such as
(a) a usage control information file (Usage File) which defines a content usage condition such as copy/playback control information and
(b) a token (Token) which is a file in which data which is, for example, a content ID as a content identifier and which is used to check and verify playback content
as files different from the content file in recording media of the content file in advance, acquiring these files before playback of content starts, checking a content usage right or verifying playback content.
To execute this processing, the current application defined by the AACS employs a configuration of specifying a directory and a file name of each file recorded in the media, individually reading the file and executing processing.
However, there is a problem that Android which provides the above operating system (OS) function does not permit an application to be executed on Android to specify a directory and a file name and individually read a file.
An apparatus which uses an operating system which has a limited function of executing this permitted application has a problem that the function of the existing content protection system (CPS) cannot be used.
When, for example, a media playback framework is pipeline-implemented as in an Android platform, a configuration of recording CPS data [a usage control information file (Usage File) or a token (Token)] in a medium as an individual file different from the content file has a problem that the CPS data cannot be easily taken by an application side.
Further, a normal media playback framework has a problem that, when a plurality of media is attached to one playback apparatus, an application cannot distinguish media.